By virtue of such features as light weight, small thickness and low power consumption, liquid crystal display devices have been used in various fields as display devices of OA equipment such as a personal computer, a TV, etc. In recent years, liquid crystal display devices have also been used as display devices of a portable information terminal device such as a mobile phone or a PDA (personal digital assistant), a car navigation apparatus, and a game machine, etc.
In the process of manufacturing the liquid crystal display device, a countermeasure to static electricity is indispensable. For example, dielectric breakdown of various wiring lines or switching elements in the active area may occur due to static electricity which has occurred in the manufacturing process or static electricity which has entered from the outside. As a countermeasure to such static electricity, for example, there is known a technique wherein the gate electrodes of two protection TFTs (configured such that their source electrodes and drain electrodes are connected in parallel in a reverse direction) which constitute a protection element are formed integral with either a gate line or a relay electrode, which is connected to a short-circuit line formed on an excess portion of the substrate.